Field of the Invention
The present invention relates to a multilayer ceramic capacitor, and particularly to a structure of an external electrode and an internal electrode of the multilayer ceramic capacitor.
Description of the Background Art
A multilayer ceramic capacitor includes a ceramic element body constituted of a plurality of layered dielectric layers, a plurality of internal electrodes arranged between the dielectric layers respectively, and a pair of external electrodes formed on the ceramic element body to be conductively connected to the internal electrodes. Ni-plating is applied to surfaces of the external electrodes to prevent dissolution into solder at the time of mounting. Further, Sn-plating is applied onto Ni-plating films to improve soldering performance at the time of mounting with soldering. The plating with Ni and Sn is typically formed by an electroplating method.
Japanese Patent Laying-Open No. 1-80011 discloses that a chemical reaction in a plating step generates hydrogen ion, and the hydrogen ion is occluded into an internal electrode and gradually reduces a dielectric layer in a periphery to cause a problem such as deterioration of an insulation resistance. It also discloses that, when an internal electrode having a noble metal (for example, Ag—Pd alloy) as a main component is used, the solution for the problem is to add metal (for example, Ni), which inactivates absorption of hydrogen, to the internal electrode.